We have a i/o for our slew in foster city that no one will put their nice boat in. (real shallow and real salty water). But we trim up after plane basically until the front end starts bobbing up and down, then we trim down a tad to get it to stop then thats the setting. ONce you do it a few times youll figure out how many seconds to hold it up till its just right, instead of doing it back and forth.

We trim at about 1/4 to 1/2 up but it's kind of hard to tell since we don't have a trim indicator. I have a hydrofoil stabilizer on the boat now so planing out can be done at optimum trim. Before that, we planed out at trim full down and then trimmed up until just before we started porpoising. We weight the front a lot more than the back for best wake shape. Most days, our only rear ballast is the crew.

have been riding the same 21 foot mod v wellcraft with a 302 for 11 years now. have never needed to trim. the wake is no comp wake, but, it is peaky and kinda steep. But it is allways firm. with three peeps or 8 it is strong. The only issue is it is touchy side to side. Got to have equal weight on both sides. Never noticed much improvment with trim, but now I will invistagate more.

we always trimmed up a little more than a 1/4 on the trim indicator. Bow weight makes it a lot easier to stay on plane and keep from porpoising. Too much weight in ours just made it too hard to stay on plane at beginner speeds.